Safety appliance for automatic hammers.



A. C. CLARK. SAFETY APPLIANCE FOR AUTOMATIC HAMMERS,

APPLICATION HLED 'AR. IT. \916. Y

Patented Nov. 28, 191%}.

' sent an annular shoulder mum w ALFRED C. CLARK, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO U. S. SAFETY APPLIANcn. COMPANY, LAND.

OF BALTIMORE, MARYLAND, A CORPORATION OF MATE? Specification of Letters Patent.

Patented Nov. as. i 2 9th.

Application filed March 17, 1916. Serial No. 84,910.

To all whom it may conccrn Be it known that I, ALFRED (l. (Titanic, a citizen of the United States of America, re siding in the city of Philadelphia. county of Philadelphia, State oi Pennsylvania. have invented certain new and useful Improvements in Safety-.Appliances for Automatic llammers, of which the following is a speci tication.

. This invention relates to a safety device for tools of the reciprocating type, retkn-rhd to hereinafter as hammers for use with a snap or set in the form of a riveter, chisel or the 'like. Such hammers ordinarily consist of a cylinder or barrel which serves as a guide for a tool,,,the same being actuated by various means known to the prior art.

The description will be confined to the application of the invention to a compressed air hammer, the use of the invention with other types of hammer being obvious in view of this description.

For convenience in changing the snap or set and because it difiic-ult to devise a convenient and operative fastening, the tool has in many instances been left free, being merely held in position by pressure against the work. However, this practice is open to the objection that if the air is turned on when the set is not on the work. or otherwise held to prevent its release from the barrel, it will be shot from the barrel which results in the loss of the tool and even in injury to workmen and passers-by.

Various means have been devised for limiting the motion of the tool. The more recent appliances for this purpose consist of a cup or thiinble passed over the end of the barrel and apertured centrally at what may be termed the bottom of the cup to pass the operative portion or end of the set and prearound the aperture to engage the flange or shoulder on the set. Such cups are illustrated in various prior patents as that to Sheehan, No. 1,125,- 890, and Clark, No. 1,055,135.

The object of the present invention is to provide effective means for locking the thimlole in position on the end'of the barrel, the same being necessarily convenient to operate 'so'that it-Inay be economical of the workmens time and. efficient as a lock in.

that it presents sutlicient resistance to the stroke of the. snap to prevent destruction of the lock and release of the snap or set when valve lever l. The barrel open to show the piston rod 5 and the tool the air is turned on and left on for a considerable time in the absence of contact with the tool and with the work. With these points in view, the applicant has produced a locking means consisting of a, key or a plurality of keys set transversely to the direc tion of the stroke and seated in a transverse slot the sides of which are in planes at right angles to the stroke and which slot or slots extend entirely through the. cup and well into themetal of the barrel. The key or keys, one to each slot, likewise present surt'ae'es at right angles to the direction of the stroke and fit closely, each in its slot. These ke vs are for convenience mounted each on a leaf spring which serves to hold them in position when once seated and prevents them from beingdislodged accidentally under any condition of operation to which they niay be subjected and at the same time permits them to be witlulrawn instantaneouslv to release the set. I

In the accompanying drawing I have illusti'ated a pneumatic hammer todthe barrel of which a safety thimble and key constructed in ac l'ordaucc with .iny invention hasbeen applied.

Figure l is a side view, the end of the barrel with the tool .or set. and the cup being shown in a central section taken on the plane oi the axis: Fig. is a side view of the thinible; and Fig. 3 is a transverse section taken on the line 3, 3 of Fig. 1 showing the thiinble and keys and barrel.

Referring to the drawing by numerals. the pneumatic hammer or riveter illustrated in Fig. 1 includes a barrel 1 having'a handle 2 with an air connection at 3 and a throttle as shown, is broken shank (ii The shank tern'iiuates in a collar 7 presenting a shoulder 8 toward the barrel and a shoulder 9 toward the operative end of the tool 10. The operation of the tool and the piston will be well understood from the preani'blcmml are in tact similar to the corresponding parts of other pneumatic riveters. The end of the tool barrel. is inclosed by a cup or thiinble 11 having; an aperture 12 concentric with its aXis oi a size to form a running fit with the operative end of the tool 10, the inside of the thimble near the end being of sulii'cient diameter to freelv admit the collar 7 on the tool. 'ln this wa of the thimble to engage the shoulder 9 on the tool, the shoulder 8 on the opposite side of the collar 7 serving to engage the end 14 o the barrel and limit the return stroke of the tool.

It is apparent that if the tool be pressed against the work and the air applied, the vibrations or blows being taken up by the work, there will be no tendency to eject the tool from the barrel but if, by any chance, as must occasionally happen, turned on when the tool is not applied to the work, there will, in the absence of the thimble 11, be nothing to limit the forward stroke and the tool will be immediately ejected with considerable force from the barrel and even in the presence of the thimble 11, if it is not held in position with the utmost rigidity, the battering effect of the-rapidly-reciprocating tool is such that the thimble will be torn ofi and the tool released. For the purpose of overcoming this tendency and preventing the release of the tool under any and all circumstances, I have provided the fastening means which is the subject of my invention. This consists of a key or keys 15 seated in the transverse registering slots 16 in the barrel and '17 in the thimble, the slots and key hav- 4 abutting surfaces at right angles to ing their the direction of-the stroke of the tool and being otherwise so arranged that the greatest possible available surface of metal is presented by both the thimble and the barrel to resist the shearing tendency set up by the hammering of the'shoulder 9 of the tool against the annular shoulder 13 of the thimble. Preferably, for the greatest strength with the least metal, the areas of surface transverse to the stroke presented by slots 16 and 17 are equal each to "he other. To hold the key or keys in. position when once seated and prevent their displacement under all conditions of operation, I provide for each key a stifi leaf spring 19 which carries the corresponding key and is secured at its base 20 to a suitable support normally stationary in regard to the barrel. The spring is preferably made so stiff that its tension cannot be conveniently overcome to withdraw the key from the slot by hand but the bottom of the slot i the barrel is so shaped that the key may be released and seated, passing into and out of the slot in the direction of the length of the slot, by rotating the thimble on the barrel.

It will thus be apparent that I have provided a fastening means so arranged that the thimble is secured to the barrel in a manner to afford the greatest possible resistance to longitudinal displacement. The keys, as shown, are so designed that the slotted port1on is approximately half the cross section of the thimble so that one-half the area of the metal is presented to the key and the other half is utilized in resisting the tensile the air be stress set up in the thimble by the action of the tool when not supported by the work. I

I have thus described my invention specifical'ly and in detail in order that its nature and operation may be clearly understood: however, the specific terms herein are used descriptively rather than in their limiting sense and the scope of the invention is defined in the claims:

1. In an automatic hammer having a barrel, a power-driven reciprocating member therein, a tool having a shank in the barrel extending into the path of the said reciprocating member, a safety thimble on the end of the barrel and means for locking the thimble in position on the barrel, consisting of a transverse key having flat surfaces at right angles to the line of reciprocation, the thim-.

ble being slotted transversely through its entire thickness, the barrel having registering slots, both slots fitting the key and having surfaces at right angles to the path of the piston to engage the correspondii'ig surfaces of the key.

'2. A safety thimble for an automatic hammer having transverse slots extending through the entire thickness of the thimble,

transverse keys in the slots and a heavy leaf spring for each key secured at one end to the 'thimble and at the other end to the key.

3. A safety thimble for an automatic hammer having transverse slots extending through the entire thickness of the thimble. the slots presenting on one side a surface equal to substantially one-half the cross-seetion of the thimble, transverse kevs in the slots and a. heavy leaf spring for each key securedat one end to the thimble and at the other end to the key.

4:. In an automatic hammer having a barrel, a power-driven reciprocating member therein, a tool having a shank in the barrel and extending into the path of the power-driven reciprocating member, a safety thimble on the end of the barrel and engaging the tool in its advanced position. means for locking the thimble in position on the barrel consisting of a transverse key having fiat surfaces at right angles to the path of reciprocation, the thimble being 1 slotted transversely through its entire thickthe slots in the thimble presenting a surface on one side at right angles to the line of reciprocation substantially equal to one-half the cross-section of the thimble, both slots fitting the.key and adapted to permit it to beinserted and withdrawn.

5, In an automatic hammer having a barrel, a power-drivenreciprocating member therein, a tool having a shank also in the barrel and extending into thepath of the power-driven reciprocating member, a safety thimble on the'end c the barrel and engagmg the tool in it, ad a ced position, means i moenii for locking the thimble in position on the barrel consisting of a transverse key having flat surfaces at right anglesto the path of reciprocation, the thirnble' being slotted transversely through its entire thickness and the barrel having registering slots, the slots in the thiinble presenting a surface on one side, at right angles to the line of reciprocation, substantially equal to one-half the cross-section of the thimble, both slots fitting the key and adapted to permit it to be inserted and Withdrawn, the surfaces of the slots in the key and the barrel being substantially equal.

(3. In an automatic hammer having a barrel, a power-driven reciprocating 1118111 bertherein, a tool having a shank in the barrel and extending into the path of the power-driven reciprocatingmember, asafety thinible on the end of the barrel. and engaging the tool in its advanced position, means for locking the thiinble in position on the barrel consisting of a transverse key having fiat surfaces at right angles to the path of rcciln'ocation, the thiinble being slotted transversely through its entire thickness and the barrel having registering slots, the slots in the thinible presenting a surface on one side at right angles to the line of reciprocation substantially equal to one-half the crosssection of the thinible, both slots fitting the key and adapted to permit it to be inserted and withdrawn, the slots in the barrel having their bottorn surface adjoining the outer cylindrical surface of the barrel so that the keys may be withdrawn from the slots in the barrel by rotating the thiinble relatively to the barrel.

7. in a pneumatic hannner having a barrel and a reciprocating piston therein, a tool having a shank in the barrel and extending into the path of the piston, a safety thiinble and means for locking the thi'inble in position on the barrel consisting of a trans verse key having fiatsurfaces at right angles to the path of the piston, the thirnble being slotted transversely through its entire thickness, the barrel having registering slots, both slots fitting the key and having surfaces at right angles to the path of the piston to engage the correspoi' ding surfaces of the key.

8. In a pneumatic hammer having a barrel and a reciprocating piston therein, a tool having ashank in the barrel and extending into the path of the piston, a safety thimble, means for locking the thimblein position on the barrel consisting of a transverse key having flat surfaces at right angles to the path of the piston, the thinible being slotted transversely through its entire thickness, the barrel having registering slots, both slots fitting the key and having surfaces at right angles to the path of the piston to engage the corresponding surfaces of the key, and a leaf spring to which the key is secured, the leaf spring serving to hold the key in position when seated.

9. In. an automatic hammer having a barrel. and a reciprocating power-driven member therein, a safety thiinble on the end of the barrel slotted transversely through its entire thickness, a transverse slot in the barrel registering with the slot in the thiinble, a key to engage both slots, having its bearing surfaces transverse to the line of reciprocation of the power-driven member, a spring for forcing the key into the slot, the slot in the barrel having its bottom surface adapted to eject the key from the slot in the barrel, when the thimble is rtated relatively to the barrel.

Signed by me at Coatcsville Pa. this th day of March, 1916.

' ALFRED C. CLARK. 

